For example, a display device is known in which a display element such as a liquid-crystal panel is used as a display screen, and a light is radiated by a backlight from behind this display element to control the brightness of an image displayed on the display screen.
The brightness of the display device is the brightness measured from the front of the display element, and typically the brightness of the display screen is adjusted by controlling the brightness of the backlight, being a light source. By lowering the brightness of the display screen using this method, it is possible to reduce the power consumption of the backlight, so that an effect of power saving can be expected.
For the display device, there are a backlight that can suppress uneven brightness effectively while achieving a reduction in power consumption, and a liquid-crystal display device using the backlight (for example, refer to Patent Document 1).
Furthermore, the display device can display a plurality of screen images on a display screen, and there is also a requirement to adjust the brightness of each of the screen images in accordance with the brightness set for each of the screen images.